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MILLIMETRON

Millimetron project

1. Objectives.
2. Principal scientific and technical parameters of the observatory.
3. Main systems of the instrument complex.
Figure 1. General view.
Figure 2. Block diagram.

1. Objectives

The project assumes creation of an international space observatory - the interferometer "Earth - Space - Space" in order to perform of astronomical investigations in millimeter, submillimeter and infrared regions with extremely high sensitivity (to a few nanoJanskies units of flux density in continuum spectrum) and extremely high angular resolution (to a parts of microsecond of arc or, possibly, nanosecond). Owing to last years research, it was established that in interval 0.4 - 10 mm there is an absolute minimum of brightness temperature of spectrum of electromagnetic radiation of far cosmos. In region 0.25 - 0.5 mm there is a deep minimum of the value vI_v, where I_v - spectral density of background intensity at frequency v. This phenomenon opens a unique possibility to create a space telescope with a mirror of 12m diameter , which will be equivalent in sensitivity to ground-based radio-telescope with solid aperture 3km diameter at 2cm wavelength, and in interferometric mode (with ground-based telescope or with similar space element ) will permit to reach an angular resolution thousand times higher than resolution of ground-based interferometer with ultimate base at the same wavelength.
Diapason of millimeter - submillimeter waves is poor explored, but contains reach and important information for cosmology and extragalactic astronomy, physics of Galaxy and galactic objects. It’s a unique possibility to observe in this spectral region a number of stars in combination with enormous angular resolution, to discover and investigate other planetary systems. At these wavelengths it is very small effect of radiation scattering due to interstellar plasma fluctuations, therefore it will be possible to obtain images of ultracompact objects, to measure with ultrahigh resolution their coordinates and moving. This diapason is extremely perspective both for researching in continuum and in atomic and molecular lines, for polarimetric measurements and for objects variability monitoring.

2. Principal scientific and technical parameters of the observatory.

Creation of the observatory assumes space launch of two satellites of "Spectrum" type with automatically deployable mirror telescopes having diameter 12 m. It’s desirable to rise accuracy of satellite orientation (rms = 1"), to reach scientific payload power consumption to 2.5 kW, and to enhance working time to 5-10 years.
There are the following possible modes of observatory functioning:

single-beam and multi-beam investigations in continuum spectrum, in spectral lines, and for polarization measurements in millimeter, submillimeter and infrared region;

interferometer "Earth - Space" in millimeter region;

interferometer "Space - Space" in millimeter and submillimeter region.

The work on creation of radio-observatory is based on the experience of creation and investigations of the largest ground-based radio-telescopes, and very-long-base interferometers, and on space interferometers projects "Radioastron" and "VSOP", infrared, submillimeter, and radio space missions IRAS, ISO, and COBE, and also missions, being prepared for launch before year 2005 - SMIM, SIRTF, MAP, COBRAS/SAMBA and FIRST. "Millimetron" project sufficiently exceeds mentioned missions in all main parameters. In accordance with preliminary considerations, it is possible to realize main requirements to space designs:

the main mirror of telescope with 12 m diameter is similar in design with mirror of projects "Radioastron" and is maintained at temperature of 3 K by a system of radiation cooling and by cryogenic machine, accuracy of surface rms = 10 mkm;
the optical system of Cassegrain type with flat periscopic tertiary mirror for guidance control;
the telescope works in bolometric single or multi-beam mode in region 3-3000 mkm, diffraction limit is realized for wavelength more than 250 mkm;
diapason 0.3-20 mm used for interferometry "Earth - Space" with participation of the largest ground-based radio-telescopes;
diapason 0.2-3 mm used for interferometry "Space - Space" between two satellites;
front-end devices of receivers and bolometers use deep cooling (down to 0.1 K);
an accuracy of orientation and stabilization rms=0.3" is achieved by adjustment of tertiary mirror;
bandwidth of transmitting information for interferometric mode up to 1 (10) GHz with ability of real-time data-reduction;
the orbit of a space-craft N^o 1 : period - about 9 days, perigee - 75 000 km, apogee - 300 000 km; the orbit is subjected to of systematic disturbances by Moon, and consequently ensures the obtaining of high quality images for any sky objects;
space-craft N^o 2 must be launched 2 - 3 years later than N^o 1 into a similar or higher orbit depending on results of investigations made during this time.

3. Main systems of instrument complex

Main systems of the instrument complex are:

the bolometric multi-beam system (~ 100 beams) for sky mapping in region 0.2 - 3 mm in continuum spectrum;
the spectropolarimetric system for investigations of objects in region 0.2 - 3 mm with resolution v/Dv ~ 3 ;
the spectropolarimetric system of high resolution up to v/Dv =3·10⁶ in region 0.2 - 3 mm;
radio-interferometric channels of the system "Earth - Space", region 0.3- 20 mm;
radio-interferometric channels of the system "Space - Space", region 0.2 - 3 mm;
the spectropolarimetric system of high resolution up to v/Dv =3·10⁶ in region 3 - 300 mkm;
the on-board system of high accuracy base frequencies and time.

Technical parameters of the observatory permit to realize a scientific program of unique investigations of all main types of astronomical objects:

discovery and research of great number of young stars, planet systems, and even single planets, their origin and evolution, search of evidence of life in the Universe;

investigation of most dense regions of the Galaxy (compact gas-dust complexes, globules), investigation of complex organic instances in interstellar medium;

investigation of relativistic stages of stellar evolution including supernova explosions, white dwarfs, neutron stars, and black holes of stellar mass;

investigation of the structure and evolution of a region around the supermassive black hole in the Center of our Galaxy, similar and more power objects in other galaxies, processes of acceleration and interaction of superenergetic particles, generated by cosmic accelerators in these regions;

detection of galaxies on stages of their originating, research of their following evolution, including investigation of evolution of stellar, gas-dust components of missing mass;

investigation of early evolution stages of the Universe from recombination moment to beginning of stars and galaxies formation.;

determination of fundamental cosmological constants and investigation of nature of missing mass, study of fundamental properties of space, time and vacuum;

high-precision astrometry for determination of distances and proper motions of stars and extragalactic objects;

search for new types of astronomical objects.

The sensitivity permits to investigate on the observatory any of more than 10 billions sky sources.

Figure 1. General view.

Figure 2. Block diagram.

If you have comments or corrections for this document, please send them via E-mail to gro@asc.rssi.ru

Best experienced with

Proposal on creation of space observatory "Millimetron" within the framework of Federal Space Program of Russia during the period until 2015.
Astrospace Center LPI RAS,
Moscow 1996